Gas sampling probe

ABSTRACT

A combustion gas sampling probe adapted for permanent installation in a high temperature region of a vapor generator is provided in the form of an elongated tubular segment whose edges are weldedly attached to the downstream side of fluid-conducting screen tubes in a manner to form a gas passage. A number of openings are provided along the length of the tubular segment to admit combustion gas to the passage. At its lower end the tubular segment connects with aspirating means, the actuation of which activates the probe to extract combustion gas from the furnace and to convey it to the exterior thereof for use.

United States Patent inventor E. Trlggs West Slmsbury, Conn. Appl. No. 874,092 Filed Nov. 3, 1969 Patented June 8, 1971 Assignee Combustion Engineering, Inc.

Windsor, Conn.

GAS SAMPLING PROBE 12 Claims, 4 Drawing Figs.

U.S. Cl 73/421.5R, 165/ 1 1 Int. Cl G01n l/26 Field of Search 73/42l.5 R, 421.5 A, 422 GC; 122/278; 236/15 E; 165/11 Reierences Cited UNITED STATES PATENTS 2,817,499 12/1957 Harding et a1. 165/1 1X 3,043,145 7/1962 Hoffman 73/4215 3,315,645 4/1967 Triggs 122/478 3,517,557 6/1970 Granger et al. .1 73/4215 Primary Examiner-Louis R Prince Assistant Examiner-Daniel M. Yasich Attorneys-Carlton F. Bryant, Eldon H. Luther, Robert L. Olson, John F. Carney, Richard E. Berneike, Edward L. Kochey, Jr. and Lawrence P. Kessler ABSTRACT: A combustion gas sampling probe adapted for permanent installation in a high temperature region of a vapor generator is provided in the form of an elongated tubular segment whose edges are weldedly attached to the downstream side of fluid-conducting screen tubes in a manner to form a gas passage. A number of openings are provided along the length of the tubular segment to admit combustion gas to the passage. At its lower end the tubular segment connects with aspirating means, the actuation of which activates the probe to extract combustion gas from the furnace and to convey it to the exterior thereof for use.

PATENTEUJUN 819?! 3583229 sum 2 OF 3 INVENTOR. LEONARD E. TRIGGS A T TOZNEY PATENTED JUN 8 I97! SHEET 3 OF 3 LEONARD E. T'Q/GGS 1 -r roe/vs Y INVENTOR.

GAS SAMPLING PROBE BACKGROUND OF THE INVENTION In the operation of vapor generators it is desirable to have the capability for extracting samples of combustion gases from the furnace chamber in order that the gases can be analyzed. The ability to analyze combustion gases is important to determine the combustion efficiency that prevails within the furnace chamber such that appropriate adjustments can be made in the operation of the vapor generator in order to optimize its performance. In this regard combustion gas samples are normally removed from the vapor generator and conducted to an Orsat or other gas analyzing apparatus where the composition ofthe gases can be determined.

The accuracy of such analysis is naturally affected by the region within the vapor generator from whence the combustion gas samples are extracted. Ideally, or most accurate results the gases should be taken directly from the furnace chamber. Combustion gas extraction from this region of the vapor generator is difficult to attain, however, due to the extremely high temperatures that exist there and the adverse affect that such temperatures have upon sampling probes, especially when no provision is made to cool the probes.

In the past, combustion gas sampling has been effected in large central station vapor generators by inserting elongated, water-cooled probe lances directly into the furnace chamber. This practice is permitted in such units due to the large amount of available space that surrounds the units whereby the insertion and extraction of elongated lances can easily be accommodated. In vapor generators of the marine type, on the other hand, such combustion gas removal practice is not permitted due to the unavailability of space within the boiler room of a maritime vessel. Gas sampling in marine units, therefore, has been effected by permanently installing a fixed probe in a low temperature region of the combustion gas pass, normally downstream of the economizer which is the lowest temperature region of the combustion gas passage through the vapor generator. The necessity of locating the sampling probes so far from the furnace chamber significantly reduces the accuracy of results that can be expected of any gas analysis done on these gases due to the fact that the gases analyzed are nonrepresentative of those flowing in the furnace chamber in that they are diluted by air leakage that occurs within the combustion gas pass between the furnace chamber and the region of the unit within which the sampling probe is located.

It is to the improvement of combustion gas sampling apparatus and procedures, especially in marine-type boilers, that the present invention is particularly directed.

SUMMARY OF THE INVENTION According to the present invention a permanently fixed combustion gas sampling probe is provided immediately adjacent the furnace chamber of a marine-type vapor generator whereby combustion gas samples representative of the gases flowing from the furnace chamber can be obtained for analysis. The probe comprises an elongated tubular segment, such as a half-tube, whose longitudinal edges are attached to the external surface of a superheater screen tube in a manner as to form a combustion gas passage by the cooperation of these two members. A number of openings are provided along the length of the tubular segment whereby gases can pass into the gas-conducting passage. The probe receives cooling by the fluid conducted through the screen tube thereby protecting it against burnout caused by the high temperatures that exist in the region of the vapor generator in which it is located. The gas-conducting passage is caused to extend to the exterior of the vapor generator in order to conduct the extracted gases to an Orsat or other gas analyzing apparatus located externally of the vapor generator.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. l is a sectional elevation of a marine-type vapor generator employing the present invention;

FIG. 2 is a detailed side elevation of a portion of the vapor generator shown in FIG. I;

FIG. 3 is a section taken along line 3-3 of FIG. 2; and

FIG. 4 is an enlarged plan section of a combustion gas sampling probe of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. I, there is shown a vapor generator 10 of a type that is particularly adapted for use in marine power plants. The illustrated vapor generator is of the twodrum type and has a tubelike enclosure or setting that is generally rectangular in horizontal and vertical section. The setting includes a boiler section 12 comprising a a pair of horizontally disposed, laterally extending upper and lower drums, l4 and 16 respectively, and interconnecting tubes 18 that fill substantially the full width of the setting. The boiler section 12 opens at its rear into a combustion gas outlet plenum 20 that houses a tubular heat exchanger 22 in the form of an economizer for preheating vaporizable liquid admitted to the circulation system of the vapor generator. At its forward end the boiler section 12 is connected in open, gas communication with a fuel fired furnace chamber 24 through a convection section 26 that houses a vapor superheater 28. The superheater 28 includes a plurality of rows of inverted U-tubes 30 that extend across the width of the unit and whose ends connect with manifold headers 32 located externally of the convection section 26.

The convection section 26 is separated from the furnace chamber 24 by rows of spaced screen tubes 34 whose function it is to shield the superheater tubes 30 against the radiant affects of combustion that occurs in the furnace chamber. The screen tubes 34 in the illustrated arrangement are riser tubes that connect at their lower ends to a lower furnace header 36 which supplies them with vaporizable liquid passed from the upper drum 14 by external downcomers The upper ends of the screen tubes 34 are laterally offset to overlie the superheater 28 and connect with the upper drum 14 whereby a continuous circulation of fluid exists in the tubes entering from the header 36 as liquid and exiting at the upper drum 14 as a liquid-vapor mixture.

Fuel burners 39 are mounted for operation within the furnace chamber 24 in burner openings 40 provided in the setting to accommodate the burners. An air plenum 42 adjacent the forward end of the unit serves to supply combustion air to the burners 39 for admixture with fuel to generate combustion gases in the furnace chamber. The combustion gases sogenerated are induced to flow sequentially through the furnace chamber 24, the convection section 26, the boiler section 12 and thence out the combustion gas outlet plenum 20.

According to the present invention means are provided to extract a portion of the combustion gases flowing from the furnace chamber 24 and for passing such gases to economizing means (not shown). This means comprises a plurality of permanently installed combustion combustion gas sampling probes $4 that are provided in the disclosed arrangement in laterally spaced locations across the width of the setting. Each of the probes comprises an elongated tubular segment 46 here shown in FIG. 4 as approximating a half-tube that is weldedly affixed to the downstream side of a screen tube 34, the cooperation between the two members defining a combustion gas extraction passage 48. Pairs of circumferentially spaced openings 50 are provided in longitudinally spaced positions along the tubular segment to establish gas communication between the interior of the vapor generator and the extraction passage 48. At their lower end each of the tub segments 46 is connected to an extension nipple 52 that connects the passage 48 with the exterior of the vapor generator setting. Air lines 54 containing sequentially operable valves 56 conduct the extracted combustion gas to an Orsat or other gas analyzing apparatus (not shown). In order to assist extraction of the combustion gases from the vapor generator, it may be desirable to provide an aspirator or the like downstream of the valves 56.

The operation of the herein-described invention is as follows. When it is desired to sample the combustion gases generated in the furnace chamber 24, one or more of the valves 36 in lines 54 are opened to effect combustion gas communication between the extraction passage 48 of the respective probes 44 and the Orsat. Single valves 56 may be opened if it is desired to sample combustion gases from each of the various sections of the furnace chamber 24 across its width or, alternatively, if it is desired to obtain a representative sample of all of the gases flowing form the furnace chamber all of the vales may be opened.

By means of the present invention, a simple, yet effective means is provided to extract combustion gas samples that are truly representative of the gases flowing through a vapor generator. By forming each probe as a tubular segment, a portion of the wall of which is formed by the exterior surface of a fluid-conducting screen tube, cooling of the probe can be effected by the fluid that serves to cool the screening tube. Since the gas sampling probe is fabricated with means for cooling it can therefore be located in close proximity to the furnace chamber where the combustion gases passed thereto will be more representative of the gas generated in the furnace chamber as compared with the sample probes of the prior art that were not cooled and, therefore, were located, of necessity, in the gas outlet plenum downstream of the liquid economizer where the gases extracted were diluted by air leakage through the setting along the combustion gas flow passage.

It will be understood that various change in the details, materials, and arrangement of parts which have been herein described illustrated in order to explain the nature of the invention, may be made by those skilled in, the art within the principle and scope of the invention as expressed in the appended claims.

What I claim is:

l. in a vapor generator in which vapor is generated by the indirect transfer of heat between high temperature combustion gas flowing through a gas enclosure and vaporizable liquid conducted through tubes contained in said enclosure, means for extracting combustion gases from a high temperature region of the vapor generator comprising:

a. an elongated tubular segment extending longitudinally of an adjacent liquid-conducting tube in said gas enclosure,

b. the longitudinal edge of said tubular segment being integrally attached to the outer surface of said adjacent liquid-conducting tube to define a gas-extraction passage, and

c. means forming openings in the surface of said tubular segment for establishing gas communication between said gas-extraction passage and the interior of said combustion gas enclosure.

2. Apparatus as recited in claim I wherein the longitudinal axis of said tubular segment is parallel to the axis of said adjacent tube.

3. Apparatus as recited in claim 1 wherein said tubular segment is a half-tube.

4. Apparatus as recited in claim wherein said tubular segment is attached to said adjacent tube on the downstream side thereof in the sense of the combustion gas flow path within said enclosure.

5. Apparatus as recited in claim 1 including;

a. means connecting said tubular segment for conducting gases flowing in said gas-extracting passage to the exterior of said enclosure, and

b. said means including a valve for activating said gas extracting means to conduct extracted gas to the exterior of said valve vapor generator.

6. In a vapor generator in which vapor is generated by the indirect transfer of heat between high temperature combustion gas flowing along a gas flow path through said vapor generator and vaporizable liquid conducted through tubes exposed to said flowing combustion gases, said vapor generator including a furnace chamber, a boiler section and an intermediate convection section housing a superheater. screen tubes separating said convection section from said furnace section and means for extracting a portion of the flowing combustion gases comprising:

a. an elongate tubular segment extending longitudinally of an adjacent screen tube,

b. the longitudinal edges of said tubular segment being weldedly attached to the outer surface of said screen tube to define a gas-extraction passage, and

c. means forming openings in the surface of said tubular segment for establishing gas communication between said gas-extraction passage and said gas flow path.

7. Apparatus as recited in claim 6 wherein the longitudinal axis of said tubular segment is parallel to the axis of said screen tube.

8. Apparatus as recited in claim 7 wherein said tubular segment is a half-tube.

9. Apparatus as recited in claim 8 wherein said tubular segment is attached to said screen tube on the downstream side thereof in the sense of said combustion gas flow path.

10. Apparatus as recited in claim 9 wherein said combustion gas extracting means includes a plurality of tubular segments attached each to adjacent screen tubes laterally spaced from one another across the width of said combustion gas flow path.

11. Apparatus as recited in claim 10 wherein each of said tubular segments includes a plurality of openings disposed on longitudinal spacing for establishing gas communication between said gas-extraction passage and said combustion gas flow path.

12. Apparatus as recited in claim 10 including:

a. gas-conducting lines connecting each of said tubular segments for conducting gases flowing in said gas-extraction passage to the exterior of said vapor generator,

b. a valve disposed in each of said gas conducting lines,

c. means for activating singly or conjunctively to selectively activate said gas extracting means. 

2. Apparatus as recited in claim 1 wherein the longitudinal axis of said tubular segment is parallel to the axis of said adjacent tube.
 3. Apparatus as recited in claim 1 wherein said tubular segment is a half-tube.
 4. Apparatus as recited in claim wherein said tubular segment is attached to said adjacent tube on the downstream side thereof in the sense of the combustion gas flow path within said enclosure.
 5. Apparatus as recited in claim 1 including; a. means connecting said tubular segment for conducting gases flowing in said gas-extracting passage to the exterior of said enclosure, and b. said means including a valve for activating said gas extracting means to conduct extracted gas to the exterior of said valve vapor generator.
 6. In a vapor generator in which vapor is generated by the indirect transfer of heat between high temperature combustion gas flowing along a gas flow path through said vapor generator and vaporizable liquid conducted through tubes exposed to said flowing combustion gases, said vapor generator including a furnace chamber, a boiler section and an intermediate convection section housing a superheater, screen tubes separating said convection section from said furnace section and means for extracting a portion of the flowing combustion gases comprising: a. an elongate tubular segment extending longitudinally of an adjacent screen tube, b. the longitudinal edges of said tubular segment being weldedly attached to the outer surface of said screen tube to define a gas-extraction passage, and c. means forming openings in the surface of said tubular segment for establishing gas communication between said gas-extraction passage and said gas flow path.
 7. Apparatus as recited in claim 6 wherein the longitudinal axis of said tubular segment is parallel to the axis of said screen tube.
 8. Apparatus as recited in claim 7 wherein said tubular segment is a half-tube.
 9. Apparatus as recited in claim 8 wherein said tubular segment is attached to said screen tube on the downstream side thereof in the sense of said combustion gas flow path.
 10. Apparatus as recited in claim 9 wherein said combustion gas extracting means includes a plurality of tubular segments attached each to adjacent screen tubes laterally spaced from one another across the width of said combustion gas flow path.
 11. Apparatus as recited in claim 10 wherein each of said tubular segments includes a plurality of openings disposed on longitudinal spacing for establishing gas communication between said gas-extraction passage and said combustion gas flow path.
 12. Apparatus as recited in claim 10 including: a. gas-conducting lines connecting each of said tubular segments for conducting gases flowing in said gas-extraction passage to the exterior of said vapor generator, b. a valve disposed in each of said gas conducting lines, c. means for activating singly or conjunctively to selectively activate said gas extracting means. 